1. Field of the Invention
The present invention generally relates to a signal conversion, and, more particularly, to a system and method of channelized signal transmission within a plesiochronous digital hierarchy (PDH) unit using ATM adaptation layers (AALs).
2. Description of the Prior Art
A plesiochronous digital hierarchy (PDH) is defined by a set of bit rates and multiplexing schemes for multiplexing of several, not necessarily synchronous, 64 kbit/s ISDN (Integrated Services Digital Network) channels into higher bit rate signals.
PDH units generally provide many types of services. One is to provide a PBX (private branch exchange) interface service, using channel associate signaling (CAS) or channelized T1 signaling. A second function is to provide a multiplexer (T1/E1/T3) interface service. Moreover, PDH units provide digital cross connection and channelized T3 services.
The data transmission format for PDH is different from the asynchronous transfer mode (ATM) data transmission format. As the use of ATM data transmission increases, the need to convert from PDH to ATM and from ATM to PDH will increase. Existing conversion solutions, however, utilize high cost, complex hardware schemes to convert and transfer the requisite data.
In light of the foregoing, there exists a need for a simplified system and process that provides for conversion from PDH to ATM data and from ATM to PDH data.